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HK: Physik der Hadronen und Kerne

HK 41: Physik mit schweren Ionen IV

HK 41.3: Vortrag

Donnerstag, 20. März 2003, 14:15–14:30, E

Measurement of the Response of the Spectators to the Participants — •V. Henzl¹, M.V. Ricciardi¹, T. Enqvist^1,2, J. Pereira³, J. Benlliure³, M. Bernas⁴, E. Casarejos³, A. Kelic¹, J. Taieb^4,5, and K.-H. Schmidt¹ — ¹GSI-Darmstadt, Germany — ²University of Jyvaskyla, Finland — ³University of Santiago de Compostela, Spain — ⁴Institut de Physique Nucleaire, France — ⁵CEA/Saclay, France

Momentum distributions of projectile fragments, formed in the reactions ²³⁸U+Pb,Ti and ²⁰⁸Pb+Ti at 1 A GeV, were measured with the high-resolution magnetic spectrometer FRS at GSI-Darmstadt. The velocities first decrease with increasing mass loss, following the Morrissey systematics, but then they level-off and increase again. Light fragments are even faster than the projectiles. According to a recent theoretical work, this finding can be interpreted as the response of the spectator matter to the participants blast. The magnitude of the longitudinal momentum gain is, according to this model, sensitive to the momentum-dependence of the nuclear mean field (NMF), and the predicted differences of the considered NMFs should be within the resolution limits of our experimental technique. This indicates that the re-acceleration of projectile spectators represents a new tool for investigating the EOS of nuclear matter.